Hydraulic circuit for controlling booms of construction equipment

Abstract

Disclosed is a hydraulic circuit for controlling booms of construction equipment, wherein working oil which is relieved from a large chamber of a boom cylinder passes through an orifice so as to prevent the boom from lowering if an overload is applied when the boom is not being operated. The hydraulic circuit for controlling booms of construction equipment includes: a boom cylinder which is connected to a hydraulic pump via a first path and a second path; a boom control valve which is mounted on the path between the hydraulic pump and the boom cylinder; a holding valve which is mounted between the boom control valve and the first path of the boom cylinder and prevents the natural lowering of a boom when the boom control valve is in a neutral position; a port relief valve which is mounted to the first path at the lower side of a holding poppet and relieves working oil when an overload is generated at the first path; and an orifice valve which is mounted at the lower side of the port relief valve, relieves the working oil which passes through the port relief valve when the boom control valve is neutral so as to relieve the working oil through an orifice, and discharges the working oil which passes through the port relief valve to a hydraulic tank at the time of conversion due to boom-up pilot signal pressure which is applied to the boom control valve.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a hydraulic circuit for controlling a boom of a construction machine. More particularly, the present invention relates to a hydraulic circuit for controlling a boom of a construction machine, in which when an overload is applied to the boom cylinder in a state in which the boom is not manipulated, a hydraulic fluid relived from a large chamber of the boom cylinder passes through the orifice so that an operator can mitigate an abrupt descending movement of the boom.BACKGROUND OF THE INVENTION[0002]A conventional hydraulic circuit for controlling a boom of a construction machine in accordance with the prior art as shown in FIG. 1 includes:[0003]a hydraulic pump 1 connected to an engine (not shown);[0004]a boom cylinder 2 connected to the hydraulic pump 1 through a first path (or a large chamber-side flow path of the boom cylinder) 2a and a second path (or small chamber-side flow path of the boom cylinder) 2b; [0005]a boom co...

AI Technical Summary

Benefits of technology

The hydraulic circuit in this construction machine prevents sudden safety accidents by controlling the movement of the boom in case of overload or constant load. This is achieved by allowing a large amount of fluid to pass through the boom cylinder and then relieve it, resulting in the boom coming down slowly and safely. This hydraulic circuit is stable and reliable, ensuring stability during use.

Problems solved by technology

Therefore, the conventional hydraulic circuit entails a problem in that there may occur safety accidents due to the abrupt descending movement of the boom.

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